1. Field of the Invention
The present invention relates generally to storage devices and methods for storing and retrieving computer data, and more particularly to systems and methods for use in emulated tape drive storage systems.
2. Description of the Related Art
With the increasing popularity of Internet commerce and network centric computing, businesses and other entities are becoming more and more reliant on large amounts of information. Protecting critical data from loss due to systems failures, virus attacks, and the like is therefore of primary importance.
Tape drives have long been a choice for storing archival back-up data in information systems. Historically, many such tape drives have used data compression to maximize the amount of data that can be stored on the tape. Tape, however, is a relatively slow and inefficient storage medium compared to hard drives or disks. Consequently emulated “tape” drives that use arrays of hard drives or disks have become more popular. For example, a hard drive may appear to a host computer or storage system as a storage tape device where data is stored, organized, and retrieved as if the hard drive is a tape storage device. The actual data may be stored in any of a variety of fashions, but will emulate or appear to the host processor and applications running that the data is stored on a physical tape storage device. For instance, the data will be stored and retrieved as a long serial sequence of data from the storage system similar to that of a physical tape storage device.
Emulated tape drive storage systems often rely on software-based data compression techniques to enable the storage of more data. Although, such compression techniques may increase the capacity of the drives and assist in emulating a tape drive capacity, the software compression techniques generally decrease the performance or speed of the input/output (I/O) operations of the storage devices because of the delay caused to serially compress the data. Therefore, software compression techniques are generally utilized, or turned “on” only when emulating tape drives and turned “off” otherwise.
Conventional storage systems that may emulate tape storage systems generally include high-speed servers having a Redundant Array of Independent Discs (RAID). Additionally, such systems may perform data protection features such as Error Correction Codes (ECC) or Cyclic Redundancy Codes (CRCs) through software based solutions. Such software-based systems generally reduce performance and speed as well.
It is desired that emulated storage tape systems have compression comparable to tape drives in order to approximately double (on average) the storage capacity of the systems while also increasing their performance. It is further desired for inexpensive RAID (either ATA or SATA) systems to have higher reliability for use in storage tape systems.